ABSTRACT
The aim of this study was to investigate the suitability of a novel electrospun polyurethane nanofibre material for water-treatment purposes. Bacterial removal efficiency was tested in the laboratory by filtering artificial water spiked with Escherichia coli through a 0.25 µm nanofibre membrane. The results were compared with those obtained using a commercial microfiltration material (MV020T) with a similar pore size (0.20 µm). Alongside the laboratory experiments, we also determined filtration efficiency with semi-pilot scale experiments using actual wastewater from the secondary sedimentation tank of a wastewater treatment plant. The laboratory experiments indicated very high log10 removal efficiency, ranging from 5.8 to 6.8 CFU (colony-forming units)/ml. These results were better than those of the commercial membrane (3.8-4.6 CFU/ml). The semi-pilot scale experiment confirmed the membrane's suitability for microbial filtration, with both E. coli and total culturable microorganisms (cultured at both 22 and 36 °C) showing a significant decline compared to the non-filtered control (wastewater from the secondary outlet).
Subject(s)
Filtration/instrumentation , Membranes, Artificial , Nanofibers , Polyurethanes/chemical synthesis , Water Purification/instrumentation , Escherichia coli , Pilot Projects , PovidoneABSTRACT
Many articles have been published on coagulant dosing in membrane bioreactors, though few have been long-term studies examining the treatment of real wastewater. This study summarises the results of a membrane bioreactor pilot-plant (flat sheet membrane, nominal pore size 0.03 µm) that treated real municipal wastewater for two-years. Both influence of phosphorus precipitation by ferric sulphate on membrane permeability (flux decrease) and soluble microbial product concentration (especially on carbohydrates and proteins) were monitored. Flux decrease over work cycles lasting several months without phosphorus precipitation were compared to two periods with precipitation. X-ray elemental diffractometry of the filtration cake showed differences in the main contributors to inorganic fouling, with decreases in Ca and Si during operation with coagulant addition, and an increase in Fe.
Subject(s)
Bacteria, Anaerobic/metabolism , Bioreactors/microbiology , Membranes, Artificial , Ultrafiltration/instrumentation , Water Pollutants, Chemical/isolation & purification , Water Pollutants, Chemical/metabolism , Water Purification/instrumentation , Equipment Design , Equipment Failure Analysis , Fractional Precipitation , Phosphorus , SolubilityABSTRACT
A seasonally operated full-scale membrane bioreactor plant (flat sheet, 0.03 µm) treating municipal wastewater from a recreation facility was monitored for 2 years. In particular, membrane bioreactor operation characteristics and development and changes in extracellular polymeric substances and soluble microbial product concentrations were observed, which were both dependent on volume and quality of incoming wastewater. Microbiological effluent quality, nutrient removal efficiency and activated sludge characteristics were analysed on a regular basis. Correlations between activated sludge quality, extracellular polymeric substance and soluble microbial product concentrations were identified. Pathogen related changes in effluent quality during plant operation were also observed. Nutrient removal efficiency was very good, despite fluctuations in influent flow.
